My First Energy Audit…Part Dos

by Erik North on January 28, 2013

OK, it’s been a few weeks but with good cause. I recently had a bad accident, breaking my ankle and right tibia. Granted that shouldn’t have affected my writing output but it is difficut to concentrate on other things when walking is suddenly out of the question.

Last post, we looked at the house I’d been investigating during my every first paid energy audit. Here we’ll look at the audit results, the recommendations and the final work that was performed.

My First Energy Audit – The Actual Audit

Maine State Housing Authority (MSHA) audits are intended to directly inform the contractor and their work scope so it involves a lot of measuring. These days I usually get a copy of the property’s tax assessor card to get all the dimenstions. For this house, we did a full schedule of all doors, windows, and dimensions, inside and out.

Looking back, the house was (and is) typical of the challenges with retrofitting older housing stock. Sometimes the building science, retrofit techniques available and older buildings don’t easy jibe. Most times this isn’t the case, and there are several companies (like our friends at Yankee Restoration) who specialize in older buildings. But it isn’t easy.

The Basement
Like I mentioned in the previous post, the foundation walls were double brick wall construction. The initial thought was spray foaming the walls, but this would prove difficult. A civil engineer with MSHA examined the structure and determined it wasn’t structural sound enough to spray foam (the load bearing wall was OK but the interior facade was crumbling in several places). Netting and densepacking cellulose in the basement ceiling was briefly discussed. However, the moisture from the sandy floor and standing water would’ve made a cellulose approach deeply problematic.

Mental note...Don't use cellulose down here

The Walls
The walls presented similar challenges. It was balloon framed construction with exterior clapboard. The cedar clapboard was original to the building, having been installed in the mid 19th century. At some point since installation, the exterior was coated with lead paint. The interior had a very thick plaster finish. So how do you insulate these uninsulated walls?

Like before, not easily. Traditionally, finished wall cavities are insulated by some manner of drilling and pumping in insulation. Without ruining the older siding or blasting lead paint dust everywhere (stripping off a course of siding and drilling or drilling right through the siding), it couldn’t be done from the outside.

An added wrinkle was that this house was in the county historical register. Any major alteration of the exterior was off the table. Even drilling through the siding, plugging and re-painting would’ve required approval.

The other possibility would be insulating from the interior. That would mean drilling holes for blowing cellulose through 1 or 2 inch thick horse hair plaster. This is not easy or pretty. Old plaster is like rock and just as hard to drill. Also, once the insulation is completed, it’s notoriously hard to hide/finish the drill holes. Contractors sometimes opt for a horizontal wood trim over trying to match the original plaster.

The Attic
The attic … the attic was in three sections, one each over the main house and two additions. Just about everything in the attic was open; the top of the exterior walls, interior walls, walk up stairways … all wide open. Oh, and uninsulated.

With older buildings, we often talk about insulating along the roof rafters. Air sealing along the attic flat in older houses can be difficult for a variety of reasons (settling of the foundation, access, extent of necessary air sealing). In this case, each of the three sections of the attic had widow’s peaks. It made air sealing the roof slope a much more difficult proposition as you’d need to tackle the ‘windows on all four sides’ widow’s peaks.

Blower Door
The blower door test came after the physical review and infrared scan of the house. After setting up, we fired the blower door up and witnessed air flying in from everywhere. The blower door read nearly 13000 CFM50 at -12 Pa. The blower door was moving several thousand cubic feet of air per minute and barely depressurizing the building.

Basically, every solid surface with the potential to leak air was doing so. Around doors, around windows, through the wall framing…like I said, basically everywhere. There was a huge amount of air sealing needed.

My First Energy Audit – The Work

Here’s where things get a bit disappointing. Maine State Housing’s low income weatherization program has set amount to spend per house, around $7000 in 2008. They can spend more but would need to pull money away from another project down the road.

It was determined that the house needed between $20k and $25k worth of work. MSHA can’t afford to commit three houses worth of efficiency work on one project so they were forced to move on.

It was an illustrating experience. I saw a spectrum of the issues that crop up with older houses, most of which I would see again. It also showed the limits of what was being done through public programs and the private sector.